Add support for channel transforms.

media/media.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'chromium_code': 1,
     # Override to dynamically link the PulseAudio library.
     'use_pulseaudio%': 0,
     # Override to dynamically link the cras (ChromeOS audio) library.
@@ skipping 159 matching lines @@
         'base/audio_renderer_mixer_input.cc',
         'base/audio_renderer_mixer_input.h',
         'base/bind_to_loop.h',
         'base/bitstream_buffer.h',
         'base/bit_reader.cc',
         'base/bit_reader.h',
         'base/buffers.cc',
         'base/buffers.h',
         'base/byte_queue.cc',
         'base/byte_queue.h',
+        'base/channel_mixer.cc',
+        'base/channel_mixer.h',
         'base/clock.cc',
         'base/clock.h',
         'base/data_buffer.cc',
         'base/data_buffer.h',
         'base/data_source.cc',
         'base/data_source.h',
         'base/decoder_buffer.cc',
         'base/decoder_buffer.h',
         'base/decryptor.cc',
         'base/decryptor.h',
@@ skipping 422 matching lines @@
         'audio/win/audio_output_win_unittest.cc',
         'audio/win/audio_unified_win_unittest.cc',
         'base/audio_bus_unittest.cc',
         'base/audio_fifo_unittest.cc',
         'base/audio_pull_fifo_unittest.cc',
         'base/audio_renderer_mixer_input_unittest.cc',
         'base/audio_renderer_mixer_unittest.cc',
         'base/bit_reader_unittest.cc',
         'base/bind_to_loop_unittest.cc',
         'base/buffers_unittest.cc',
+        'base/channel_mixer_unittest.cc',
         'base/clock_unittest.cc',
         'base/data_buffer_unittest.cc',
         'base/decoder_buffer_unittest.cc',
         'base/djb2_unittest.cc',
         'base/filter_collection_unittest.cc',
         'base/multi_channel_resampler_unittest.cc',
         'base/pipeline_unittest.cc',
         'base/ranges_unittest.cc',
         'base/run_all_unittests.cc',
         'base/seekable_buffer_unittest.cc',
@@ skipping 676 matching lines @@
             'media',
           ],
           'sources': [
             'tools/media_bench/media_bench.cc',
           ],
         },
       ],
     }]
   ],
 }